Time delay mechanism



Oct. 12, 1965 D. POPOVITCH 3,211,099

TIME DELAY MECHANISM Filed 001,- 51, 1963 I r 31 H 3o\ 32 '2 g l IFIG.2. 9 X

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' Y PROJECTILE SPIN AXIS IN VEN TOR. DRAGOLYOUB POPOVITCH United StatesPatent 3,211,099 TIME DELAY MECHANISM Dragolyoub Popovitch, LakeParsippany, N .J assignor to the United States of America as representedby the Secretary of the Army Filed Oct. 31, 1963, Ser. No. 320,581Claims. '(Cl. 102-79) (Granted under Title 35, US. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government for governmental purposes without the payment to meof any royalty thereon.

The present invention relates to time fuzes forrelatively-small-diameter artillery and other ammunition, and moreparticularly to mechanisms for effecting a predetermined time delay inthe operation of such fuzes in projectiles of the type referred to.

It is an object of the present invention to provide an improvedtime-delay mechanism for artillery and like projectiles of relativelysmall diameter that can be adapted to a limited space requirement andoperate more safely and effectively.

A time delay, as is understood, is required to prevent a projectile fromfiring or detonating in the gun tube or barrel and also for a safedistance beyond the gun position. The problem is to insure such timedelay for ammunition of small diameter where allowable space for thetime delay mechanism is limited both by the inside and the outsidediameters of the whole fuze, compatible with the small caliber of theprojectile.

It is a further object of the invention to provide an improved fuzetiming mechanism adapted for use with a ball-type rotor, containing thedetonator, of a fixed diameter while retaining a fixed andrelatively-small outside fuze diameter and a desired degree ofcompactness.

In accordance with one form of the invention, a hollow ball rotor in afuze is subjected to a predetermined braking torque by a helical-typespring element adjustably tightened into frictional engagement as awrapping about the diameter. This reduces the angular velocity of theball rotor in aligning its axis of symmetry in flight with the spin axisof the round or projectile in which it is mounted. The time required forthe rotor to do this is the time delay.

Prior designs developed to insure a required time delay for a fuze usinga ball type rotor element of fixed diameter did not attain the desiredfixed and relatively-small outside diameter of the body, and thus, thedesired compactness of construction. The use of ball bearings around therotor, to minimize friction between the fuze body and the rotor,required more space than was readily available. There was no control ofthe friction, and hence, of the force due to the spin transmitted fromthe body to the rotor for its alignment with the spin axis. A time delaymechanism in accordance with the invention overcomes these and otherproblems.

The invention will, however, be further understood from the followingdescription of a specific embodiment thereof, when considered withreference to the accompanying drawing, and its scope is pointed out inthe appended claims.

In the drawing,

FIG. 1 is a top view of a fuze, for use with an artillery shell or likeprojectile of relatively small diameter, embodying the invention, and

FIG. 2 is a sectional view, in elevation, of the fuze of FIG. 1, showingfurther details of construction in accordance with the invention.

Referring to the drawing, the fuze structure comprises a ball rotor orrotor element 5 within a housing assembly comprising a main cylindricalbody 6 and an end cap or closure element 7 fitted into the hollowcentral end open- 3,211,099 Patented Oct. 12, 1965 ing' or socket 8therein for the rotor. Both the cap 7 and body 6 are provided withbearing surfaces 9 and 10 for the rotor. The body 6 thus provides a seatfor the rotor in which it is retained by the cap 7. The cap is providedwith a closure plate 11 having a central opening 12 and has a tightfrictional fit with the cap 7. An outer cover element 14 fits over thecap as indicated.

A helical 'timing control spring 16 of a few turns or convolutions isaffixed or connected at one end to the main body in a suitable lockinghole 17 and at the other end to the cap 7 in a similar hole 18. Itencircles the rotor on a diametral line and frictionally engages theouter surface thereof. A set of predetermined tool holes 20 and 21 arelocated in the peripheral surface portions of the rotor on oppositesides of a firing or locking-pin hole 22 which is alignable with thelongitudinal axis YY of the housing assembly. The holes 20 and 21 areused in measuring the torque or braking action applied by the springwhen tightened or loosened by turning the end cap 7.

The rotor is provided with a hollow interior in the form of a tubularopening or passageway 23 extending therethrough diametrically on an axisXX. This is the axis of symmetry of its mass or body and is normally setat a predetermined angle, as indicated, with respect to the longitudinalaxis YY of the fuze. The passageway is adapted to contain the fuzedetonator which may fire after it is aligned with the axis YY and incommunication with an opening 24 for a chamber 25 in the body of thefuze. An additional set of holes 20', 21' and 22 in the rotor surface onthe opposite side of the axis XX from the holes 20, 21 and 22 areprovided to maintain the symmetry of the rotor about said axis.

The axis YY is aligned with and is the same as the spin axis of thewhole projectile with which the fuze is connected, as indicated inoutline at 26. The rotor is locked in the safety position shown, withthe axis of symmetry XX and the passageway 23 at the predetermined angleto the spin axis Y-Y, by a locking or firing pin 27 which seats in orengages the locking hole 22 and extends through the coverplate opening12 and a bearing bracket 28 on the plate, with a free sliding fit. Abiasing spring 29 of the coiled compression type surrounds the firingpin 27 between the coverplate 11 and a stake or through-pin 30 extendingtransversely of or diametrically through the pin 27. This is in latchingengagement with and forms part of centrifugally-actuated orspin-responsive release means for the firing pin including and indicatedby fly weights 31 and 32 which move in the direction of the arrows bycentrifugal force and clear the stake or latch element 30 when theprojectile is fired or launched and attains full rotational speed aboutthe spin axis YY. This unlatches the stake or latch element 30 and thefiring pin 27. The latter is then free to move under spring bias todisengage from the locking hole 22 and unlock the rotor. As any suitablespin-responsive latching or locking means for the rotor may be providedfurther description is not believed to be necessary.

When the projectile is fired and has attained full rotational speed itis safely clear of the gun site before it is fully armed after unlockingthe rotor, due to a delay action imparted to the rotor. When in flight,the fuze structure rotates about the axis YY and the ball rotor isforced by centrifugal action on the mass centers thereof to turn aboutan axis perpendicular to the plane of the drawing as viewed in FIG. 2until its axis of symmetry XX coincides with the spin axis YY. Afterunlocking, the time delay in doing this is a function of the brakingtorque applied by the control spring 16. This, in turn, is adjusted byrotation of the end cap 7 as described, and can be set with a highdegree of accuracy at the time of manufacture so that only slightchanges are needed at any later time for a predetermined desired delaytime. This relation can be established by appropri ate tests and thuscan be used for manufacturing purposes. The influence of manufacturingtolerances and quality of finishes in the bearing surfaces and the like,can be compensated to achieve a more uniform time delay in theproduction run of such devices. The device may thus be armed in flightwith any desired and accurate margin of safety for firing on impact, asthe firing pin, time-delayed into alignment therewith, is driven back orotherwise made to strike the detonating charge.

From the foregoing description it will be seen that the problem ofproviding accurate and effective time delay action in fuzes forammunition involving projectiles of small diameter is met in accordancewith the invention by a simplified construction. In this a ball rotorcontaining the detonator is set and locked with its axis of symmetry atan angle to the spin axis of the projectile with which the time delaymechanism is used. The rotor is unlocked and is then subjected to apredetermined braking torque by a coiled spring element wrapped andtightened around the rotor to reduce its angular velocity in turning andaligning its axis of symmetry with the spin axis of the round orprojectile before detonating.

I claim:

1. A time-delay mechanism for artillery fuzes and the like, comprisingin combination, a ball rotor adapted to receive a detonating charge andhaving a predetermined axis of mass symmetry, a cylindrical bodyelement, means in said body element providing a seat for said rotor, arotatable end cap mounted on said body and providing a retaining meansfor said rotor, means for mounting said body with the longitudinal axisthereof along and coextensive with the spin axis of a projectile inflight, and means including a coiled spring surrounding and directlyfrictionally engaging a surface of said rotor along a diametral line forsubjecting said rotor to a braking torque and a timing delay in movingto bring said rotor into a firing position for said charge and said axisof symmetry into alignment with the spin axis from a fixed angularsafety position with respect thereto.

2. A time-delay mechanism as defined in claim 1, wherein the spring isconnected at one end with the body and at the other end to the rotatableend cap, thereby to vary the tension on the spring and the timing delayby rotation of said end cap.

3. A time-delay mechanism as defined in claim 2, wherein the ball rotoris provided with a passageway therein extending along said axis ofsymmetry for receiving and holding said detonating charge, and wherein afiring pin element is positioned in said body and adapted to moveaxially to release said rotor from said fixed angular position inresponse to a stable rotational speed of said body element and to firesaid charge on impact and following said time delay.

4. A time-delay mechanism for artillery fuzes and ammunition ofrelatively small diameter comprising in combination, a ball rotor havingan open passageway extending therethrough along an axis of symmetrytherefor, said passageway being adapted to receive and hold a detonatingcharge, a cylindrical fuze body having an end opening therein andproviding a seat for said rotor, a cap element providing an end closuremeans for said opening and retaining means for said rotor, means formounting said body with the logitudinal axis thereof aligned With thespin axis of a projectile with the fuze body attached thereto, said capelement and body being frictiona'lly connected and relatively rotatableabout said spin axis, a helical-type control spring surrounding therotor and directly frictionally engaging a portion of the outer surfacethereof along a diametral line spin-releasable means for holding saidrotor with said axis of symmetry at a predetermined angle with respectto the spin axis and the longitudinal axis of the body, and meansproviding end connections for the spring with said body and cap element,whereby relative rotational movement thereof changes the tension of saidspring and frictional timing control of rotor movement in response tospin of said body and alignment of said axes one with the other uponrelease of said rotor for fuze detonation.

5. A time-delay mechanism for artillery fuzes and the like, comprisingin combination, a ball rotor having an open-ended passageway thereinextending along an axis of symmetry of said rotor, said passageway beingadapted to receive and hold a detonating charge, a cylindrical bodyhaving an end opening and means therein providing a seat for said rotor,a rotatable end cap for said body providing a closure means for saidopening and retaining means for said rotor, means for mounting said bodywith the longitudinal axis thereof along and coextensive with the spinaxis of a projectile fuze, a coiled spring element surrounding the ballrotor and directly frictionally engaging a portion of the outer surfacethereof, spin releasable means for holding said rotor with the axis ofsymmetry at a predetermined angle With respect to the longitudinal axisof said body and the spin axis, and means providing end connections forsaid spring element with the body and the cap, whereby relativerotational movement thereof changes the spring tension and frictionaltiming control of rotor movement in response to spin of said body andalignment of said axes one with the other for fuze detonation.

References Cited by the Examiner UNITED STATES PATENTS 2,663,260 12/53Thompson 102-73 2,921,527 1/60 Guerne l0979 2,924,176 2/60 Neuwirth eta1. 10279 X 2,978,982 4/61 Bianchi 10279 SAMUEL FEINBERG, PrimaryExaminer.

BENJAMIN A. BORCHELT, Examiner,

1. A TIME-DELAY MECHANISM FOR ARTILLERY FUZES AND THE LIKE, COMPRISINGIN COMBINATION, A BALL ROTOR ADAPTED TO RECEIVED A DETONATING CHARGE ANDHAVING A PREDETERMINED AXIS OF MASS SYMMETRY, A CYLINDRICAL BODYELEMENT, MEANS IN SAID BODY ELEMENT PROVIDING A SEAT FOR SAID ROTOR, AROTATABLE END CAP MOUNTED ON SAID BODY AND PROVIDING A RETAINING MEANSFOR SAID ROTOR, MEANS FOR MOUNTING SAID BODY WITH THE LONGITUDINAL AXISTHEREOF ALONG AND COEXTENSIVE WITH THE SPIN AXIS OF A PROJECTILE INFLIGHT, AND MEANS INCLUDING A COILED SPRING SURROUNDING AND DIRECTLYFRICTIONALLY ENGAGING A SURFACE OF SAID ROTOR ALONG A DIAMETRAL LINE FORSUBJECTING SAID ROTOR TO A BRAKING TORQUE AND A TIMING DELAY IN MOVINGTO BRING SAID ROTOR INTO A FIRING POSITION FOR SAID CHARGE AND SAID AXISOF SYMMETRY INTO ALIGNMENT WITH THE SPIN AXIS FROM A FIXED ANGULARSAFETY POSITION WITH RESPECT THERETO.